Fix Web Server Is Down Error Code 521 – A Complete Guide

Don’t let Cloudflare’s Web Server Is Down – Error Code 521 affect your site’s performance.

Is Your Website Showing Error Code 521? Here’s How to Fix It!

Seeing “Web Server Is Down – Error Code 521” on your website? This error commonly occurs when Cloudflare is unable to connect to your web server. If left unresolved, it can cause downtime, traffic loss, and frustrated users.

Let’s break down why this happens and how you can fix it quickly.

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Error Code 521

What Is Error Code 521?

Cloudflare Error 521 means that Cloudflare tried to reach your web server but it refused the connection. This happens when:
✓ Your web server is down or unresponsive.
✓ Cloudflare IP addresses are blocked by your server’s firewall.
✓ Your origin server isn’t properly configured to accept Cloudflare requests.

Server Configuration

Why Does Cloudflare Show ‘Web Server Is Down’ Error Code 521?

Cloudflare operates as a gateway which connects your website to site visitors. When users visit your site:

Cloudflare performs an online status check for your website.
The Error 521 message will display if your server rejects the connection attempt.
The error page becomes visible to visitors instead of your website content.

The issue stems from your server rather than Cloudflare’s system. The server configuration issue can be resolved by fixing it.

Fix Web Server

How to Fix Web Server Is Down Error Code 521

1. Check If Your Web Server Is Running

Restart your server and check if it’s accessible.
Try accessing your site directly via IP address (bypassing Cloudflare).
If the site loads without Cloudflare, the issue is likely Cloudflare’s connection to your server.

2. Whitelist Cloudflare IP Addresses

Your firewall or security software might be blocking Cloudflare’s IPs.

Check your firewall settings and allow Cloudflare’s IP ranges (find them in Cloudflare’s official documentation).
Disable mod_security or similar security modules temporarily and test.

3. Verify Your SSL/TLS Settings

Mismatched SSL settings can cause connection failures.

Ensure your Cloudflare SSL mode matches your server’s SSL setup (Full or Full (Strict) mode recommended).
If you have Let’s Encrypt, update your SSL certificates if they’ve expired.

4. Restart Your Web Server and Check Logs

Use SSH or hosting panel to restart Apache, Nginx, or LiteSpeed servers.
Check server logs for error messages related to blocked requests.

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Prevent Future Error

Prevent Future Error 521 Issues

✔ Enable Automatic Server Monitoring – Use Uptivol’s monitoring tools to track server health.
✔ Optimize Your Firewall Settings – Avoid mistakenly blocking Cloudflare IPs.
✔ Update Your Web Server Regularly – Keep Apache, Nginx, and LiteSpeed updated.
✔ Use a Reliable Hosting Provider – Ensure your hosting supports Cloudflare compatibility.

Find Other Monitoring Tools

Why Choose Uptivol for Server Monitoring?

🔹 Instant Downtime Alerts – Get notified the moment your web server is down.
🔹 Real-Time Monitoring – Track your website’s uptime and server response.
🔹 Easy Troubleshooting Tools – Diagnose and fix errors quickly.
🔹 Cloudflare Compatibility – Works seamlessly with Cloudflare-protected websites.

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FREQUENTLY ASKED QUESTIONS

Questions? We have got Answers!

How does Uptivol notify me when my website goes down?

Uptivol continuously monitors your website’s availability. If downtime is detected, you’ll receive an instant website down email notification, along with options for SMS or push alerts.

Can I customize who receives the downtime notifications?

Yes! You can set up alerts for multiple recipients, such as your IT team, hosting provider, or key stakeholders.

How often does Uptivol check my website for downtime?

Uptivol performs real-time monitoring at set intervals, ensuring you’re notified immediately when an issue is detected.

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